2024年02月18日:霍格天体 : 近乎完美的环状星系-（Hoag's Object: A Nearly Perfect Ring Galaxy） 2024年02月18日:霍格天体 : 近乎完美的环状星系-（Hoag's Object: A Nearly Perfect Ring Galaxy）--原图下载{mtitle title="霍格天体 : 近乎完美的环状星系"/}Image Credit: NASA, ESA, Hubble; Processing: Benoit Blanco说明: 这是一个星系还是两个？在1950年，当天文学家霍格偶然发现这个不寻常的河外天体后，大家就得面对这个问题。 这个天体醒目的外环，主要是由明亮的泛蓝恒星所组成，中心的球核，主要的成员是可能远更老的泛红恒星，而一道几乎完全黝黑的缝隙横亘在二者之间。霍格天体是如何形成的，包括它的恒星和气体为何会聚成近乎完美的圆环，至今仍然不明。众多的形成假说之一认为：数十亿年前发生过星系碰撞，而原先造成这种重力效应的核心棒后来消失了。 这幅主题影像是由哈伯太空望远镜所拍摄的，最近再用人工智慧的去噪讯演算法重新处理过。 不过，无线电波段的观测指出，在过去数十亿年之间，霍格天体并未吸积另一个小星系。 霍格天体位于北天的巨蛇 座方向，大小约有100,000光年，距离则在6亿光年左右。 在影像右侧可见到许多远在后方的星系，而且很凑巧的，在暗隙的七点钟方向，还有另一个更遥远的环状星系。（Hoag's Object 霍格天体）{lamp/}原文：{mtitle title="Hoag's Object: A Nearly Perfect Ring Galaxy"/}Image Credit: NASA, ESA, Hubble; Processing: Benoit BlancoExplanation: Is this one galaxy or two? This question came to light in 1950 when astronomerArthur Hoagchanced upon this unusual extragalactic object. On the outside is aring dominated by bright blue stars,while near the center lies a ball of much redder starsthat are likely much older. Between the two is agap that appears almost completely dark. How Hoag's Object formed, including its nearly perfectly round ring of stars and gas, remains unknown. Genesis hypotheses include agalaxy collisionbillions of years ago and the gravitational effect of acentral bar that hassince vanished.The featured photo was taken by theHubble Space Telescopeand reprocessed using an artificially intelligent de-noising algorithm. Observations in radio waves indicate that Hoag's Object has not accreted a smaller galaxy in the past billion years. Hoag's Object spans about 100,000light years and lies about 600 million light years away toward the constellation of the Snake(Serpens). Many galaxies far in the distance are visible toward the right, while coincidentally, visible in the gap at about seven o'clock, is another but more distant ring galaxy.

2024年01月07日:猫眼星云：可见光及X射线波段的景观-（The Cat's Eye Nebula in Optical and X-ray） 2024年01月07日:猫眼星云：可见光及X射线波段的景观-（The Cat's Eye Nebula in Optical and X-ray）--原图下载{mtitle title="猫眼星云：可见光及X射线波段的景观"/}Image Credit: NASA, ESA, Hubble Legacy Archive;Chandra X-ray Obs.; Processing & Copyright: Rudy Pohl说明: 有人认为它形似猫眼，不过也有人认为，它或许较像庞大的海螺 壳。它其实是一颗类太阳恒星，在生命短暂壮丽末期抛出的气体所织就的，也是现知最明亮结构最清晰的行星状星云之一。这团星云滨死的中心星，或许在一系列规律的脉动里，抛出了外层 气壳，形成星云外围的同心壳层结构。然而，美丽複杂但对称的美丽内围结构，到底是如何形成的，目前仍不全然了解。这幅主题影像组合了经过数位锐化的哈伯太空望远镜影像，以及钱德拉天文卫星拍摄的X射线影像。这座漂浮在太空中的精美雕塑，宽约半光年。当人们望进这只猫眼时，或许同时也预见了太阳的宿命，有一天，它会演化到行星状星云阶段…只不过这得再过50亿年左右。{lamp/}原文：{mtitle title="The Cat's Eye Nebula in Optical and X-ray"/}Image Credit: NASA, ESA, Hubble Legacy Archive;Chandra X-ray Obs.; Processing & Copyright: Rudy PohlExplanation: To some it looks like a cat's eye.To others, perhaps like a giant cosmic conch shell. It is actually one of the brightest and most highly detailed planetary nebula known, composed of gas expelled in the brief yet glorious phase near the end of life of a Sun-like star.This nebula's dying central star may have produced the outer circular concentric shellsby shrugging offouterlayers in a series of regular convulsions.The formation of the beautiful, complex-yet-symmetric inner structures, however, is not well understood.The featured image is a composite of a digitally sharpened Hubble Space Telescope image with X-ray light captured by the orbiting Chandra Observatory. The exquisite floating space statue spans over half a light-year across.Of course,gazing into this Cat's Eye,humanity may well be seeingthe fate of our sun, destined to enter its ownplanetary nebulaphase of evolution ... in about 5 billion years.

2023年10月03日:MyCn 18：沙漏星云-（MyCn 18: The Engraved Hourglass Planetary Nebula） 2023年10月03日:MyCn 18：沙漏星云-（MyCn 18: The Engraved Hourglass Planetary Nebula）--原图下载{mtitle title="MyCn 18：沙漏星云"/}Image Credit & Copyright: NASA, ESA, Hubble, HLA;Processing & Copyright: Harshwardhan Pathak说明: 你看见沙漏结构了吗？或者它在看你？如你想像力够用的话，MyCn 18的众多环状结构叠成一个沙漏，而沙漏孔形似一只眼睛。不论如何，位于这个形似沙漏的行星状星云内的中心星，来日已不多了。当类太阳恒星耗尽核燃料之后，它会抛出外层的气壳，经历这种短暂且美丽的恒星生命终结阶段，而其核心则会成为一颗逐渐冷却变暗的白矮星。在1995年，天文学家用哈伯太空望远镜，针对行星状星云拍摄了一系列影像，包括成为上面这幅影像主题的这团星云。在影像中，可以看见纤细的多环状辉光（氮为红、氢绿和氧蓝）所构成的纤薄沙漏管面。这种空前清晰的哈伯望远镜影像，所清楚呈现的云气抛射过程之细节，将有助于解开像MyCn 18这种行星状星云的複杂形状和对称性等神祕待解的难题。{lamp/}原文：{mtitle title="MyCn 18: The Engraved Hourglass Planetary Nebula"/}Image Credit & Copyright: NASA, ESA, Hubble, HLA;Processing & Copyright: Harshwardhan PathakExplanation: Do you see the hourglass shape -- or does it see you? If you can picture it, the rings of MyCn 18 trace the outline of an hourglass -- although one with an unusual eye in its center. Either way, the sands of time are running out for the central starof this hourglass-shapedplanetary nebula.With its nuclear fuelexhausted, this brief, spectacular, closing phase of a Sun-like star's life occurs as its outer layers are ejected - itscore becoming a cooling, fadingwhite dwarf.In 1995, astronomers used theHubble Space Telescope(HST) to make a series ofimages of planetary nebulae, including the one featured here. Pictured, delicate rings of colorful glowing gas(nitrogen-red,hydrogen-green, andoxygen-blue) outline the tenuous walls of thehourglass.The unprecedented sharpness of the Hubble images has revealedsurprising details of the nebula ejection process that are helping to resolvethe outstanding mysteriesof the complex shapes and symmetries of planetary nebulas like MyCn 18.

2023年09月25日:Arp 142：蜂鸟星系-（Arp 142: The Hummingbird Galaxy） 2023年09月25日:Arp 142：蜂鸟星系-（Arp 142: The Hummingbird Galaxy）--原图下载{mtitle title="Arp 142：蜂鸟星系"/}Image Credit: NASA, ESA, Hubble, HLA;Processing & Copyright:Basudeb Chakrabarti说明: 这个螺旋星系发生了什么事？近在数亿年前，影像中这二个大星系位在上方的NGC 2936，很可能还是一个正常的螺旋星系，自顾自的旋转、创造恒星、忙自己的事。后来，它太靠近下方的庞大椭圆星系NGC 2937，于是情况就急转直下。因其标誌性的外观而有蜂鸟星系之称的NGC 2936，在近距离重力交互作用的扰动下，不但方向发生了偏移，外观也出现了扭曲。在黝黑星际尘埃细丝的后方，可见到由明亮泛蓝恒星所构成的鸟喙，而螺旋的中心则像一只眼睛。此外，合称为Arp 142的这对星系，在某些人的眼里形似鼠海豚或在抱蛋的企鹅。这幅经过重处理的极细緻主题影像，是哈伯太空望远镜最近所拍摄的影像之一。Arp 142位于长蛇座方向约3亿光年远之处。大约在10亿年之内，这2个星系可能会合併成一个更大的星系。（Hummingbird Galaxy 蜂鸟星系；Porpoise Galaxy 鼠海豚星系）{lamp/}原文：{mtitle title="Arp 142: The Hummingbird Galaxy"/}Image Credit: NASA, ESA, Hubble, HLA;Processing & Copyright:Basudeb ChakrabartiExplanation: What's happening to this spiral galaxy?Just a few hundred million years ago, NGC 2936, the upper of the two large galaxies shown at the bottom, was likely a normal spiral galaxy -- spinning, creating stars -- and minding its own business.But then it got too close to the massive elliptical galaxy NGC 2937, just below, and took a turn.Sometimes dubbed the Hummingbird Galaxy for its iconic shape, NGC 2936 is not only being deflected but also being distorted by the close gravitational interaction.Behind filaments of dark interstellar dust, bright blue stars form the nose of the hummingbird, while the center of the spiral appears as an eye. Alternatively, the galaxy pair, together known as Arp 142, look to some like Porpoise or a penguin protecting an egg.The featured re-processed image showing Arp 142 in great detail was taken recently by the Hubble Space Telescope.Arp 142 lies about 300 million light years away toward the constellation of the Water Snake (Hydra).In a billion years or so the two galaxies will likely merge into one larger galaxy.

2023年06月19日:礁湖星云喧嚣的中心-（The Busy Center of the Lagoon Nebula） 2023年06月19日:礁湖星云喧嚣的中心-（The Busy Center of the Lagoon Nebula）--原图下载{mtitle title="礁湖星云喧嚣的中心"/}Image Credit: NASA, ESA, Hubble; Processing: Francisco Javier Pobes Serrano说明: 礁湖星云的中心正在进行剧烈壮观的造星活动。在影像的中心附近，至少可以找到两根长约半光年、由极强烈恒星风和高能量星光吹袭而成的漏斗形云柱。而附近极端明亮的恒星Herschel 36，则照亮了整个区域。此外，还可见到红化或遮掩其他炽热年轻恒星的厚重尘埃云墙。随着这些恒星的能量流进冰冷的尘埃和云气，横跨在毗邻区域巨大温差所形成的剪向风，可能就是造就这些漏斗云柱的主因。上面这张宽约15光年的影像，是由哈伯太空望远镜所拍摄的6色照片组合而成。编录号为M8的礁湖星云，位在黄道上的人马 座方向，离我们约5,000光年远之处。{lamp/}原文：{mtitle title="The Busy Center of the Lagoon Nebula"/}Image Credit: NASA, ESA, Hubble; Processing: Francisco Javier Pobes SerranoExplanation: The center of the Lagoon Nebula is a whirlwind of spectacular star formation.Visible near the image center, at least two long funnel-shaped clouds, each roughly half a light-year long, have been formed by extreme stellar winds and intense energetic starlight. A tremendously bright nearby star, Herschel 36, lights the area. Vast walls of dust hide and redden other hot young stars. As energy from these stars pours into the cool dust and gas, large temperature differences in adjoining regions can be created generating shearing winds which may cause the funnels. This picture, spanning about 15 light years, combines images taken in four colors by the orbiting Hubble Space Telescope. The Lagoon Nebula, also known as M8, lies about 5000 light years distant toward the constellation of the Archer (Sagittarius).

2023年06月02日:M101-（Messier 101） 2023年06月02日:M101-（Messier 101）--原图下载{mtitle title="M101"/}Image Credit: NASA,ESA,CFHT,NOAO;Acknowledgement -K.Kuntz (GSFC),F.Bresolin (U.Hawaii),J.Trauger (JPL),J.Mould (NOAO),Y.-H.Chu (U. Illinois)说明: 庞大美丽的螺旋星系M101，是着名梅西叶星表所收录的最后一个天体，但这绝不代表它最不起眼。这个跨幅约170,000光年的庞大星系，大小几乎是我们银河系的2倍。在19世纪罗斯伯爵使用帕森城大望远镜进行观测时，M101是透过此望远镜见到的首批"涡状星云"之一。上面这幅由哈伯太空望远镜团队所发布、涵盖M101中心约40,000光年区域的影像，除了组合哈伯望远镜在20和21世纪拍摄的51张照片之外，也整合了地面望远镜的影像数据，成为历年来记录螺旋星系的最高画质影像之一。这幅无比清晰的影像，清楚的呈现这个正向星系盘面恒星和尘埃所聚成的特徵结构，以及后方的背景星系，有些甚至透过M101直接可见。亦称为风车星系的M101，位在北天的大熊座之内，离我们约有2千5百万光年远。{lamp/}原文：{mtitle title="Messier 101"/}Image Credit: NASA,ESA,CFHT,NOAO;Acknowledgement -K.Kuntz (GSFC),F.Bresolin (U.Hawaii),J.Trauger (JPL),J.Mould (NOAO),Y.-H.Chu (U. Illinois)Explanation: Big, beautiful spiral galaxy M101 is one of the last entries inCharles Messier'sfamous catalog, but definitely notone of the least.About 170,000 light-years across, this galaxy is enormous, almosttwice the size of our own Milky Way.M101 was also one of the originalspiral nebulaeobserved by Lord Rosse's large 19th century telescope, theLeviathanof Parsontown.Assembled from 51 exposures recorded by theHubble Space Telescopein the 20th and 21stcenturies, with additional data from ground based telescopes,this mosaic spans about 40,000 light-years across the central regionof M101 in one of the highest definitionspiral galaxy portraits ever released from Hubble.The sharp image shows stunning featuresof the galaxy's face-on disk of stars and dust along withbackground galaxies, some visible right through M101 itself.Also known as thePinwheel Galaxy, M101lies within the boundaries of the northern constellationUrsa Major, about 25 million light-years away.